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  <title>需求</title>

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</div><hr /><div id="image.requirements" class="section">
  <h2 class="title">需求</h2>
  <p class="para">
   If you have the <acronym title="Graphics Draw">GD</acronym> library (available at <a href="http://www.libgd.org/" class="link external">&raquo;&nbsp;http://www.libgd.org/</a>) you will also be able to create
   and manipulate images.
  </p>
  <p class="para">
   The format of images you are able to manipulate depend on the
   version of <acronym title="Graphics Draw">GD</acronym> you install, and any other libraries
   <acronym title="Graphics Draw">GD</acronym> might need to access those image formats.
   Versions of <acronym title="Graphics Draw">GD</acronym> older than gd-1.6
   support <acronym title="Graphic Interchange Format">GIF</acronym> format images, and do not support
   <acronym title="Portable Network Graphics">PNG</acronym>, where versions greater than gd-1.6 and less than
   gd-2.0.28 support PNG, not GIF. <acronym title="Graphic Interchange Format">GIF</acronym>
   support was re-enabled in gd-2.0.28.
   <blockquote class="note"><p><strong class="note">Note</strong>: 
    <span class="simpara">
     Since PHP 4.3 there is a bundled version of the <acronym title="Graphics Draw">GD</acronym>
     lib. This bundled version has some additional features like alpha
     blending, and should be used in preference to the external library
     since its codebase is better maintained and more stable.
    </span>
   </p></blockquote>
  </p>
  
  <p class="para">
   You may wish to enhance <acronym title="Graphics Draw">GD</acronym> to handle more image formats.
   <table class="doctable table">
   <caption><strong>Supported image formats</strong></caption>
    
     <thead>
      <tr>
       <th>Image format</th>
       <th>Library to download</th>
       <th>Notes</th>
      </tr>

     </thead>

     <tbody class="tbody">
      <tr>
       <td><em>gif</em></td>
       <td class="empty">&nbsp;</td>
       <td>
        Only supported in <acronym title="Graphics Draw">GD</acronym> versions older than gd-1.6 and newer than
        gd-2.0.28. <em class="emphasis">Read-only
        </em> <acronym title="Graphic Interchange Format">GIF</acronym> support is available with PHP 4.3.0 and the bundled
        GD-library. <em class="emphasis">Write</em> support is available since
        PHP 4.3.9 and PHP 5.0.1.
       </td>
      </tr>

      <tr>
       <td><em>jpeg</em></td>
       <td><a href="http://www.ijg.org/" class="link external">&raquo;&nbsp;http://www.ijg.org/</a></td>
       <td>
        When building the jpeg library (prior to building PHP) you
        must use the <strong class="option configure">--enable-shared</strong>

        option in the configure step.  If you do not, you will receive
        an error saying <em>libjpeg.(a|so) not found</em>
        when you get to the configure step of building PHP.
       </td>
      </tr>

      <tr>
       <td><em>png</em></td>
       <td><a href="http://www.libpng.org/pub/png/libpng.html" class="link external">&raquo;&nbsp;http://www.libpng.org/pub/png/libpng.html</a></td>
       <td>
        Only supported in <acronym title="Graphics Draw">GD</acronym> versions greater than gd-1.6.
       </td>
      </tr>

      <tr>
       <td><em>xpm</em></td>
       <td><a href="ftp://metalab.unc.edu/pub/Linux/libs/X/!INDEX.html" class="link external">&raquo;&nbsp;ftp://metalab.unc.edu/pub/Linux/libs/X/!INDEX.html</a></td>
       <td>
        It&#039;s likely you have this library already available, if your system
        has an installed X-Environment.
       </td>
      </tr>

     </tbody>
    
   </table>

  </p>

  <p class="para">
   You may wish to enhance <acronym title="Graphics Draw">GD</acronym> to deal with different fonts. The following
   font libraries are supported:
   <table class="doctable table">
   <caption><strong>Supported font libraries</strong></caption>
    
     <thead>
      <tr>
       <th>Font library</th>
       <th>Download</th>
       <th>Notes</th>
      </tr>

     </thead>

     <tbody class="tbody">
      <tr>
       <td><em>FreeType 1.x</em></td>
       <td><a href="http://www.freetype.org/" class="link external">&raquo;&nbsp;http://www.freetype.org/</a></td>
       <td>本过时特性<em class="emphasis">将</em>肯定会在未来被<em class="emphasis">移除</em>。</td>
      </tr>

      <tr>
       <td><em>FreeType 2</em></td>
       <td><a href="http://www.freetype.org/" class="link external">&raquo;&nbsp;http://www.freetype.org/</a></td>
       <td class="empty">&nbsp;</td>
      </tr>

      <tr>
       <td><em>T1lib</em></td>
       <td><a href="ftp://sunsite.unc.edu/pub/Linux/libs/graphics/" class="link external">&raquo;&nbsp;ftp://sunsite.unc.edu/pub/Linux/libs/graphics/</a>)</td>
       <td>
        Support for Postscript Type 1 fonts.
       </td>
      </tr>

     </tbody>
    
   </table>

  </p>
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